Field of the Invention
The present invention relates to the field of piezoelectric crystals and piezoelectric crystal composites operating for high frequency as well as a system and method for a design and fabrication of piezoelectric stacks exhibiting reduced driving voltage while maintaining driving level for transducer applications. More particularly, the present invention provides a novel and improved system and method for designing and fabricating piezoelectric d35 shear mode crystal stacks with improved performance in transducer arrangements,
Description of the Related Art
Conventionally, PMN-PT based piezoelectric single crystals have superior dielectric and piezoelectric properties compared to the traditional PZT ceramics. To more fully exploit the excellent properties of single crystals, crystal composite have been fabricated to improve electromechanical coupling coefficients and thus transducer performance characteristics.
For ultrasound transducers, the operating frequency is often but not exclusively inversely related to the thickness of the piezoelectric material. Thus, as targeted operating frequency increases, the thickness of the piezoelectric material decreases accordingly and this induces operative and electromechanical difficulties. On the other hand, an optimal aspect ratio has been attempted for the piezoelectric crystal pillars in order to maintain a high electromechanical coupling coefficient for piezoelectric composites as has been illustrated by the applicants related granted and pending applications.
A conventional piezoelectric stack is generally used to reduce the driving voltage while maintaining the same driving level/field. It is useful especially when piezoelectric materials are too thick to drive under normal conditions. A stack concept is commonly adopted in some transducer designs such as tonpilz transducers. Generally a thin solid metal shim piece is placed between two piezoelectric elements and bonded with conductive epoxy. The metal shim is mainly for electrical connection and completely covers each piezoelectric element. Such arrangements for tonpilz transducers typically only work in d33 mode, wherein a clamping effect in general is not a major concern. Unfortunately as a severe detriment, using other modes is prohibited. Accordingly, there is a need to provide an improved method and system for stack design for a piezoelectric system that addresses a concern and provides improved efficiencies.